Why forked Apache Commons Math

[pkernevez]

Hi,

We are looking for a Mathematics lib (mainly focus on optim now).
We found Hipparchus, but I didn't found the motivation to fork from Apache instead of continuing to contribute to it.
What are they and why choose one or the other ?

Thanks,
Philippe

[maisonobe]

Hi @pkernevez

This is a delicate questions…
The fork occurred in 2016, and Hipparchus was in fact created by many of the people that were previously developing Apache Commons Math. The split was due to incompatible views within the team. Some were related to the overall Commons policy that were considered too strict with respect to evolution, which blocked some developments. Some were just plain difficult relationship between people.
At the time of the fork, Apache Commons Math was 3.6.x, almost 10 years later it is still there (there is a beta for 4), but mainly the library has been split into different parts (numbers, random)... Hipparchus has add 17 releases during this period. Hipparchus is used operationally in some critical operations (it is the basis of Orekit which is used worldwide and is used in operational systems to fly satellites).

If you are interested in optimization, you can look at the develop branch of Hipparchus, we added constrained optimization in late 2023 and recently (last week) it was improved again by a contributor.
Choosing between the two is both a matter of content (we did add a lot of things since the fork, and Apache Commons Math or its split libraries did add a lot of things on their side too), and a matter of maintenance.